Implement and test InitializerDependencyGraph.

An InitializerDependencyGraph is a directed acyclic graph (DAG) of named
initialization operations.  Every node in the graph has a unique name, a
behavior function, and a set of prerequisites.  The graph supports two
inspection functions, one to get the behavior function for a node with a given
name, and the other to produce a vector of node names, ordered in a manner that
does not violate any preprequisite dependneces.

InitializerDependencyGraph is exception-free, and because it is for use very
early in process startup, it does no logging itself.

This patch also introduces a utility macro, MONGO_MAKE_STRING_VECTOR, which is
useful for constructing std::vector<std::string> from a sequence of string
literals.  This patch uses it for testing, but subsequent MONGO_INIT-related
work will rely on it, as well.

Part of work on SERVER-5112.

1 files changed, 8 insertions, 0 deletions

diff --git a/src/mongo/base/status.h b/src/mongo/base/status.h
index 616055bbbf8..088dd5483ba 100644
--- a/src/mongo/base/status.h
+++ b/src/mongo/base/status.h
@@ -114,6 +114,14 @@ namespace mongo {
         static void unref(ErrorInfo* error);
     };
 
+    static inline bool operator==(const ErrorCodes::Error lhs, const Status& rhs) {
+        return rhs == lhs;
+    }
+
+    static inline bool operator!=(const ErrorCodes::Error lhs, const Status& rhs) {
+        return rhs != lhs;
+    }
+
     //
     // Convenience method for unittest code. Please use accessors otherwise.
     //